Therapeutic eye treating apparatus and method



Oct. 13, 1964 v M. E. KRAMER 3,152,594

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M. E. KRAMER 3,152,594

THERAPEUTIC EYE TREATING APPARATUS AND METHOD Oct. 13, 1964 RT. LATERALGENICULATE MACULAR AREA M-PAPILLO MACULAR BUNDLE 3RD.ORDER NEURON OPTICRADIATIONS OPTIC NERVE FIBERS PURE coma SYSTEM -BIPOLAR CELLS I ST.,2ND. AND 3 RD. ORDER NEURONS OF THE VISUAL TRACT FIG. I9

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S A a mm M DWM 2 C N d R0 8 M A N .ER 1 AP 0 DDU Mi E R RE F E l HG ER 1ZON Y EVERI ST KRAMER ATTORNEY United States Patent "ice 3,152,594TEFIERAFEUTIC EYE 'I'REA'IING APPARATUS AND ME'IHGD .MaryEveristKramendfi W. Cataiina Drive,

Phoenix, Filed Aug. 29, 1961, Ser. No. 134,631)

12 Claims. (Cl. 123395) central area of the eye retina willbe protectedfrom com-' plete light adaptation, while a specific and selected retinalarea receives the light stimulus from high intensity illumination withthe resulting effect of light adapting said retinal area.

It is another object of this invention to provide a viewing device suchas described above wherein the center of the source of illumination isblocked off with an opaque strip which uniquely protects the centralarea of the eyeretina from exposure to the high intensity illumination.

It is another object of this invention to provide an object of attentionby means of a fixation dot, centrally placed inthe opaque strip of theviewing device such as described, for the further purpose of obtainingaccurate and central fixation of the eye during. exposure of theselected peripheral retinal area to the high intensity illumination.

It is yet another object of this invention to provide a method oftherapeutically treating the eye, in which a negative after-image isproduced upon a selected periph eral retinal area while the centralfoveal-niacular area of the eye is caused to aim toward the center.

It is yet another object of this invention to provide a method oftherapeutically treating the eye, in which the eye receives the stimulusto aim to the center by means of the fixation dot while simultaneouslybleaching the visual purple of a selected peripheral retinal area, bymeans of high intensity illumination; after which stimulus the resultingafterimage on the peripheral retinal area will act as a frame ofreference for continued central (iovealmacular) fixation while viewingafixation point in ordinary room lighting conditions.

It is yet another object of this invention to provide a method oftherapeutically treating an eye, which, through incorrect position orposture, has received an incorrect light stimulus (relative to thenormal fellow eye), and has, through practice, learned to make incorrectresponse to said stimulus. By presenting a correct stimulus with thecentroscope, the eye in turn can learn to make the correct response. g

It is yet another object of this invention to provide a simple andinexpensive training device for daily eye practies at home, for patientswhose eye conditions would benefit from such therapy, including patientswho cannot, because of long distance or'transportation difficulties,make the necessary trips to the eye therapist. It is possible also, forpatients who cannot afford therapy with other devices currentlyavailable, to use this invention at home.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds when taken in connection withthe accompanying drawings, in which:

3,1525% Fatented Get. 13, 1954 FIGURE 1 is an isometric viewer" myimproved therapeutic instrument; i v I FIGURE 2 is a longitudinalsectional view taken along line 22 in FIGURE 1; i' v FIGURE 3 isasectional detail view taken along line 3-3 in FIGURE 1;

FIGURE 4 is a transverse sectional view taken along line 44 in FIGURE 1;

FIGURE Sis a transverse sectional view taken along line 5-5 in FIGURE 1;is

FIGURE 6 is a graph showing certainproperties of various commerciallyavailable materials suitable for use as a dark adaptive filter in thepresent invention;

FIGURE 7 is a schematic View illustrating the manner in which the retinaof the eye is stimulated and inhibited simultaneously with theinstrument; 7 v

FIGURE 8 is a schematic view illustrating a condition of imagesuppression in the eyes; i

FIGURE illustrates the positive afterimage seen with a closed eyefollowing two successive exposures to the high intensity light with theinstrument held horizontally and vertically, respectively;

FIGURE lOillustrates the negative afterimage seen with the eye openwhile looking at the letter M on a light colored wall and after twosuccessive exposures to high intensity light during which the instrumentis held horizontally and vertically, respectively;

FIGURE 11 illustrates the negative afterirnage seen with the eye openwhile looking at the letter M on a light colored wall after one exposureto light with the in strument held vertically;

FIGURE 12 is a' View similar to FIGURE 11 but illustrating the negativeafiteri-mage resulting from exposure to light with the instrument heldhorizontally;

FIGURE 13 is a schematic view ofthe right eye showing certain partsthereof;

FIGURE 14 is a schematicview illustrating the rod system of the retina;i

FIGURE 15 is a view similar to FIGURE 14 illustrating the cone system ofthe retina;

' FIGURE 16 is a schematic view illustrating the arrangement of thenerve fibers in the retina;

FIGURE 17 is a graph illustrating the relation of visual acuity of theretina to the distance from the fovea;

FIGURE 18 is a schematic viewshowing the distribution of retinal nervefibersof the left eye, with placement of centroscope image and fixation,and

FIGURE 19 is a view schematically illustrating the relationship of the1st, 2nd and 3rd order neurons to other components of the eye retina. i

The 'centroscope is a device to assist the patient with oculardifliculties resulting from inability or loss of central fixation in oneor both eyes. With proper use of the centroscope, the patient canrestore or establish central fixation. With the establishment of centralfixation, the patient may then enjoy the rewards of increased visualacuity, straight eyes and a normalfusion reflex pattern.

Loss of central fixation can occur from various causes of a functionalor pathological nature. It is the loss of -centralfixation 'offunctional origin that is benefited by use of the centroscopep Inselected cases of pathology that are cured, a residual functional maladycan be treated with the cen'tro scope to restore central fixation.

' Central fixation in this context refers to foveal fixation. Duringtreatment procedures, the macular area around the fovea may be used bythe patient; therefore, the term "foveal-macular area ofthe retina. Thecentral foveal vision is' almost exclusively cone vision. The fovealarea is surrounded bythe macula and this .region contains fective inscotopic vision. The cone vision is most ffective in photopic vision andform vision.

Simply stated, the ccntroscope brings about central fixation byrendering ineffective the rod vision with maximum light stimulus. Itleaves no alternative for cone vision in the foveal-macular area, but toaim at the specified fixation point.

To accomplish the fixation with the central foveal area of the eye, theccntroscope illustrated in the accompanying drawings is employed. Theword ccntroscope is derived from three Greek words optikos, tropos andkentron which, when translated to English, means eye that turns to thecenter.

The centroscope comprises a black rectangular box or housing It havingend sections 11 and 12 removably secured in the respective opposite endsby any suitable means such as screws 14. End section 11 has threadablymounted therein a lamp socket 15 equipped with a con ventional switch16. An elongated incandescent lamp globe 17 is threadably secured intosocket 15, said globe extending longitudinally of and substantiallyparallel to the interior side walls of housing 10.

The light housing it may be either rectangular or circular in shape, butshould be black in color. The globe 17 used in the current model ismanufactured by General Electric Company and other electricalmanufacturers; and is a clear, 40 watt, 120 volt, Tl0, showcase lamp,with a class B, C-8 filament and approximately 430 lumina, therebygiving the effect of a 600 foot candlepower when the eye viewing it issix inches in front of the instrument.

On the top, back and bottom side walls of the housing It) are smallholes 18 for the purposes of dissipating the heat generated from thelight source 17. These holes are of some importance when severalconsecutive treatments are to be performed.

Suitable elongated slots or openings 21 are provided on the front sideof wall 19a of the housing 16, said slots being located on oppositesides of a central viewing mechanism broadly designated by the referencecharacter 22 and specifically comprising a target opening 23 and a darkadaptive filter 24 covering the opening. The area of the filter 24viewable through opening 23 constitutes a fixation dot, usually red. Thefilter 24 is removably held in position over the target opening 23 byany suitable means such as a grooved projection 25 and a spring clip 26(see PEG- URE 5). In the present model, each slot 21 is 1% inches longand 7 inch wide. The length of the slot is governed by the length of thefilament in lamp globe 17. Inside the housing It) is a light reflectinglining 27 of aluminum foil or other suitable material.

As will be apparent from the detailed description appearing in thespecification, the purpose of the shielding of the central retina is toproduce the optimum photochemical adaptation for maximum visual acuity.The filter 24, along with the protective shield around it, does thisprecisely and effectively, irrespective of the distance the ccntroscopeis held from the eye. The retina is exposed to the ccntroscope while thefovea is aimed at the filter 24. Immediately following this exposure,the vision in the central area is enhanced because (1) this area hasattained optimum photochemical adaptation for acuteness of vision, and(2) greater accuracy of fixation. The former is brought about by theprevious shielding of this area by filter 24 and the opaque shield orwall 22a around it. The latter occurs because the previously stimulatedperipheral area is photochemically adapted so that it cannot react to alight stimulus and therefore its previously conditionedstimulus-response patterns cannot interfere with the fixation refiex.Since this area i completely light adapted, other inhibitory influencesare operative during this period which prevent other reflexes, visual orvestibular, to

function. The fixation refiex has complete freedom to function withoutinterference, modification or alteration. The afterimage in theperiphery acts as a closed door, giving the fixation point in space aframe of reference. Thus, the fixational response cannot shift from thecentral to the exposed peripheral area, nor can a previously conditionedpattern interfere.

During therapeutic exposure, the foveal-macular area of the eye retinais adapted to be aimed at the abovernentioned colored fixation dot offilter 24, which dot is surrounded by opaque black area 22a and, at thesame time, unfiltered light of relatively high intensity is projectedfrom source 17, through slots 21, and onto selected peripheral retinalareas of the eye (see FIGURE 7). It is here seen that the foveal-macularretinal area F is prepared for maximum stimulation with filtered light,and that the peripheral retinal area is prepared for maximum inhibitionwith the stimulating light. Since the middle area of the light source 17is viewed through the protective light filter 24 of viewing mechanism, aphotochemical change in the foveal-macular retina does not occur. Theexposed peripheral areas of the retina are bleached (light adapted),rendering them ineffective to receive a light stimulus for seconds (orminutes) after the exposure can receive a light stimulus following theinitial exposure.

In FIGURE 1 it will be observed that the two slots 21, through whichselected peripheral retinal areas of the eye are exposed to unfilteredlight of high intensity, are 10- cated equidistantly on diametricallyopposite sides of the viewing mechanism 22 through which thefoveal-macular area of the eye is simultaneously exposed to a filteredlight capable of supplying a fixation stimulus but without lightadapting it. Thus the location of viewing mechanism 22 is determinedwith reference to the positions of slots 21, the latter serving asguides or reference areas. As will be described more fully hereinafter,afterimages may be elicited from and retained on the selected peripheralretinal areas of the eye thus exposed by subsequently viewing asecondary light stimulus. The exposed fovealmacular area, however, willnot produce or retain an afterimage while viewing the secondarystimulus. Nevertheless the correct location of the foveal-macular areamay be readily determined by referring to the positions of the retainedafterimages on the peripheral retinal areas. Therefore, the retainedafterimages constitute a frame of reference designating the central areaof the eye.

With the ccntroscope, the patient does the viewing in the center throughthe filter 24 of viewing mechanism 22. The operator supervises andguides this viewing or fixation or" the central foveal area. Thus thecentral viewing mechanism blocks off the foveal-macular area from lightexposure. The red dot on filter 24, made visible through opening 23 bylamp 17, is a fixation device which induces the foveal-macular area tohold steady. Should the fovea slip off the red dot, there is someprotection afforded the;

area surrounding the fovea by virtue of the opaque wall portionsdisposed between openings 21 and 23 and de- This is of majorsignated byreference characters 22a. importance, since foveal fixation is verydifiicult and many times impossible to maintain in the beginning. If thearea around the red dot or opening 23 were not blocked off, then thefoveal area would also be bleached or light adapted if the fixationslipped from the fovea onto a surrounding area. The fovea fixates on thered dot at 23, While the macular area surrounding it is protected by theopaque or blocking areas 22a of the ccntroscope (FIG- URES l and 6).

Viewing the red dot through the opening 23 prevents a change of thephotochemical substance in the fixating or viewing foveal-macular areaof the retina by the patients own effort to look at the round red dotand the operators guidance to assist the patient to maintain steady,accurate fixation with the foveal-macular area during the exposure ofthe selected peripheral retinal area to the bleaching light. The fovealaiming or fixation on the small round spot of filtered light duringexposure of the selected peripheral retina to the bright illumination isof vital importance for efifective therapy (FIGURE 18).

A greater stimulus and therefore better response for foveal fixation isgiven with the red dot on filter 24, which dot is illuminated by lightsource 17 behind it. A totally dark target area would afford no fixationstimulus, the latter being an essential requisite in centroscopetherapy.

The opaque black blocking wall portions 220 vary in width from 5 to 15millimeters which, in turn, serve to shield or protect the centralfixating area of the eye retina from bleaching and becoming lightadapted from the light emitted from slots 21. The lO-millimeter width isthe one most commonly used; the greater 15-millimeter width is used formore severe cases and the lesser width of S-rnillimeters for less severecases.

The dark adaptive filter may comprise a ruby red glass, red Kodaloidmanufactured by Eastman Kodak Company of Rochester, New York, orPlexiglas manufactured by Rohm & Haas Company of Chicago, Illinois (seeFIGURE 6), or acrylic cellulose acetate, or other material having thesame or substantially the same light transmission and which eliminatesall but 10 to percent of the red portion of the visible spectrum.

FIGURE 6 explains the photometric curves of the visible spectrum,typical of the various Plexiglas colors. To protect the central retinalarea sufficiently, it is necessary to eliminate all but about 10 to 15percent of the red portion of the visible spectrum in order that nobleaching, sufiicient to form an afterimage, will result. This isaccomplished by using red of sufficient density, or by combining variouscolors such as red-blue or redgreen or red-amber-blue of variousdensities so that only 10 to 15 percent red light transmission occurs.This is done so that no afterimage is formed in the foveal-macular areafollowing the centroscope stimulus, indicating that no bleaching of thephotochemical substance has occurred. v

Any light transmissible material which will protect the fovea frombleaching of its photochemical substance other than that accomplished byordinary room lighting, yet maintain sufficient brightness as a fixationstimulus, is a suitable medium for viewing through the central viewingmechanism 22. Red Scotch tape, commonly used for Christmas wrapping, hasbeen used effectively for this purpose.

Where change from the standard techniques is indicated, it has beenfound that this can be done by changing the distance between the eye andthe centroscope, foreshortening the distance for greater brightness, and'increasing the distance between the eye and the centroscope for lesserbrightness. In those cases of so-called eccen tric fixation where thevision is so markedly reduced that the patient has no ability to aim orfixate with the foveal-macular area of the retina, then it is necessaryfor the operator to supervise carefully and instruct the patient tofixate on a point that would bring the foveal-macular area into linewith the central viewing mechanism, thereby sparing it from theinhibitory and bleaching effects.

Although defined in specific terms above, it is evident that thecentroscope may assume a variety of structural sizes and forms withoutdeparting from the spirit of this invention.

THE RED FILTER FOR DARK ADAPTATION Investigators in the field of darkadaptation have not been able to explain physiologically Why red lightpreserves the dark adaptation of the retina. Advising the use of the redfilter to achieve dark adaptation is based on the following experiment:Following an exposure to red light, dark adaptation is much faster thanfollowing a pre-exposure to white light. This completely confirms thepractical experience of the last war. All personnel engaged in nightflying, where dark adaptation was of importance, wore red goggleswhenever they were exposed to light bright enough to interfere withtheir dark adaptation. According to Hecht and Hsia, researchers in thisfield (Hecht, S., and I-Isia, Y: Dark Adaptation Following LightAdaptation to Red and White Lights, I. Optic. Soc. America 35:261, 1945)the real reason why red light or red transmitting glasses or filters areused for achieving dark adaptation depends on the relative positions ofthe two luminosity curves on the wave length scale of the spectrum. Theeffectiveness of the transmitted red light is the area under the curveto the right of a vertical line at 620 millimicrons (FIG. 6). For thephotoptic curve the ratio between the relative brightness of the wholelight compared to the red light is nearly 10, which means that if, forthe cones, whole white light is to be made equal in brightness to thered light transmitted from it through the red filter, the whole lighthas to be reduced its intensity by means of a neutral filter or anyother device which decreases it evenly along the spectrum. The realvalues depend on the energy distributions in the spectrum of the lightused and the transmission of the filter. It is thus seen that red lightis more effective than white when used for the purpose of maintainingdark adaptation. The red filter is used also as a therapeutic device instrabisrnus when the subject is sensitive to light and has a tendency toclose one eye when going outdoors into ordinary bright daylight or intoa room with bright illumination.

PHYSIOLOGICAL SIGNIFICANCE FIGURE 13 schematically illustrates therelative positions of various parts of the right eye. The fovea iscomposed entirely of cones. These cones are the most sensi tive to lightand are able to distinguish the finest detail.

To quote Adler, p. 536, Physiology of the Eye, C. V. Mosby Co.: The purecone system (fovea) is made up of the following three links; the cones,the bipolars and the ganglion cells (see FIGURES l3, l8 and 19). Eachcone is synaptically related to a single bipolar which, in turn, issynaptically connected to a single ganglion cell. Each of these unitsseems to function quite differently from that of the rod system, inwhich several rods are connected to the same bipolar cell. The pure conesystem cannot have spatial summation, whereas in the rod system a largetaint patch of light may stimulate a whole group of rods so that theirindividual responses can be added together until they reach thethreshold necessary to send an impulse through one nerve fiber. Thissystem can respond to light of lower intensity than can the cone system,even though the sensitivity of the single rods might be assumed to be nogreater than that of the single cones. Hence those areas which havesingle receptors connected to one nerve fiber have great discriminationin detail, whereas the areas in which there is considerable spatialsummation have lower thresholds for the detection of light, and areespecially useful for the detection of movement of objects in the visualfield.

The remainder of the macula is composed of a combination of cones and avery few rods. This section of the retina is capable of resolving veryfine detail. Proceeding outward from the foveal-rnacular area more andmore rods are present and at the same time fewer and fewer cones untilthe extreme periphery of the retina contains about 10 rods for everycone. In the foveal area each cone is synaptically connected to a singleganglion cell. In the rod system, several rods are connected to the sameganglion cell.

The retina is unlike a photographic plate in that its properties are notfixed. The sensitivity of the photo graphic plate cannot be immediatelyaltered to meet the requirements of different intensities ofillumination, Whereas the retina within a relatively short time canadapt itself to changes in brightness level. Another quality of theretina in which it dilfers from a photographic plate is the response incertain nerve fibers when the light is turned off. This response isgoverned by the intensity of the preceding illumination and the durationor" the stimulus. Consequently each region is affected by what is goingon in surrounding areas so that the eifects of stimulation are notstrictly localized in extent. The activity of the retina depends,therefore, partly upon changes due to previous stimulation and partlyupon activities taking place in other regions of the retina at the timeof stimulation. These effects are known as temporal and spatialinduction.

There are three principal layers of nerve cells in the retina of the eye(see FIGURES i4, 15, 16 and 19); the rods and cones, which are thereceptors, the bipolar cells (1st order neuron) which mediate the B andC response below, and the ganglion cells (2nd order neuron), whichfibers travel up the optic nerve to connect with the 3rd order neuron inthe visual centers of the brain (FTGURE 19). These nerve cells are alsojoined to one another in a variety of combinations of cross connections.Thus the retina is a true nerve center, no less complex than other partsof the central nervous system. The retinal fibers react to the lightstimulus.

A stimulus is any energy that elicits a response from the nerve fiber.The response is in the nature of an electrical discharge, which istransformed into a nerve message. Each nerve responds in a particularmanner to a stimulus and never gives any other kind of response,regardless of the condition of stimulation or the adaptation of thefiber for the stimulus.

There are three distinct types of responses of dilferent fibers in thesame eye. He shall identify these responses as A, B, and C.

Response A.The fiber responds with a rapid burst of impulses when thelight is turned on, soon dies down to a steady slower discharge. Thereis no response to cessation of illumination in this fiber.

Response B.The fiber gives the same as the previous one but the impulsestops immediately although the light is kept on. The B fibers respond tovery slight changes in intensity, the greater the change the more markedthe response. The B fiber is very sensitive to any movement of theretinal image.

Response C.The fiber gives no response whatever when the light is turnedon, or through the whole duration of illumination, but when the light isturned of, there is a rapid burst of impulses. It is the C response thatis utilized for spatial induction with the centroscope. The discharge ofimpulses in the C fibers signalling cessation of stimulation must not beheld to imply that these fibers are actively responding to darkness orthe absence of light, but rather some process is developing in theretina during illumination, which is identical with inhibition, stoppingthe discharge in these fibers upon re-illumination.

The B and C types of responses occur in the bipolar and ganglionicstructures which are interposed between the rods and cones. In order forthe C response to be given oil, the receptor must be prepared for thisresponse by the effect of the light stimulus; for only if previouslyprepared by the stimulus can they function when it is removed. Thus itis, that the peripheral retina is stimulated for a definite period oftime with high intensity of illumination with the centroscope, toprepare it for the inhibition immediately following the exposure(FIGURES l0 and 18). It is not uncommon to find that the retina, ifexposed for seconds to the centroscope light, will retain thisinhibitory response for several minutes. The afterimage formed by thebleaching can frequently be recalled hours afterwards, both positive andnegative afterimages.

At all levels of illumination between complete light adaptation andcomplete dark adaptation, the retina makes every effort to come intoequilibrium with any change of illumination. Below the level of 0.1meter candle, the rods (peripheral retina) alone function. Above thislevel, the cones begin to function (fovea). As the illuminationincreases still further, the complete bleaching of visual purple stopsrod function entirely and vision at high levels of illumination is duesolely to cone function, which is the case after centroscopestimulation. At intermediate levels, both cones and rods are active.

Light which is absorbed affects a photochemical reaction in the retina.This reaction is the primary and probably the least complicated part oftransforming light energy into a nerve impulse. The substance in theretina having the property of absorbing portions of the visible spectrumis called a pigment. A photosensitive pigment is present in the rods andhence confined to the peripheral retina. It is called rhodopsin orvisual purple. It is not definitely known to applicant whether or not itis present in the cones of the foveal area of the retina. Thephotochemical substance in the cones has not been identified.

Light has the effect of bleaching the visual purple to visual white. Inthe absence of light, visual purple is reformed. When an eye issubjected to continuous illumination, the visual purple is bleached bythe light and is also being reformed, thus striking a balance betweenthe rate of bleaching and the rate of regeneration. This steady state ofbalance between catalysis and synthesis remains as long as theillumination remains unchanged. Thus the retina, by chemical andpossibly electro-physiological changes, can adapt itself to meet therequirements of different intensities of light. Also, each region of theretina is affected by what occurs in surrounding areas, therebymodifying or enhancing the local stimulation. When the activity of theretina is affected by changes due to previous photic stimulation it iscalled temporal induction, a time value; if affected by activitiestaking place in other regions of the retina, it is called spatialinduction, a simulataneity of spatial perception. Centroptics utilizesboth temporal and spatial induction for its effectivcness.

APTERIMAGES Afterimages are the transient, fluctuating sensations whichoccur after the primary image has disappeared. They vary according tothe manner in which the retina is stimulated. When the retina isstimulated by a bright light, the primary image of the light is seen. Ifthe eyes are closed following this exposure, an image of the light ofthe same shape will atpear, an afterimage. A positive afterimage is onewhich has the same color and shape as the stimulating light. It iseasily seen with the eyes closed, or in a darkened room with the eyesopen, or with the eyes directed at a dark background. A negativeafterimage has the same form as the stimulating light, but is of adifferent color from that of the stimulus. A secondary light stimulus, alight colored wall for example, is usually needed for its elicitation.When a light stimulus produces a positive afterimage, no other stimulusof a like nature can elicit a response from the exposed area of theretina because of the inhibition produced by the afterimage. It does,however, react to stimuli of an opposite kind, a secondary stimulus,thereby eliciting an afterimage, usually opposite to the firstafterimage (positive afterimage, than negative). Afterimages may remainfor seconds only, or recalled hours later. A positive afterimage iseasier to obtain and retain than a negative afterimage.

The negative afterimage which originates from centroscope stimulationhas many gradations of color, or it may be negative and positivesimultaneously; the central area of the afterirnage may be positive, theouter, surrounding area negative, varying from light green, blue,orange, red to purple. A normal negative afterimage is dark purple whenthe stimulating light is that of the white light of the centroscope(FIGURES 10 and 18). Before reaching the dark purple stage it may beyellow, green, orange, red, blue, then purple.

As stated before, afterimages result from photochemical processes in theretina. However, since afterimages can be conditioned with practice, itcannot be denied naent of her vision was doubtful.

that higher sensory areas may influence their intensity and duration bythe reinforcement-of repetition. The photochemical process is the Betaadaptation of the retina to photic stimulation and is confined exactlytothe retinal area stimulated, eventhough a small portion ofthe retinahas been stimulated. The Alpha sensitivity applies to the entire retinaeven though only a small portion ofthe retina has been stimulated. Thisprocess represents the ervous system and is quicker in its responsethan'the Beta response. When stimulated with the centroscope, the Alphaadaptation presumablyreintorces the Beta response of the retina. Thoughthe central processes may exert inhibitory influences onafterirnages,-it is certain they do not take their origin in the highercenters. (Crai'd W Origin oiVisual After-Images, Nature, London, 154:512, -l940.-)

Binocular fixation can result only from normal monocular fixation inboth eyes. Poor monocular fixation may result from low visual acuity or"disease of the-retina in the'foveal area. Rarely does it occur asaresult of impaired development of the proprioceptive mechanism. The eyemay wander rather than be fixated or directed to the object so that theimage does not fall on the fovea. This is spoken of as eccentricfixation. The centroscope is primarily for the purpose of (1.) restoringmonocular central fixation, then (2) binocular central fixation.

USAGES (1) Amblyopia (Loss of Vision) in One or Both Eyes From VariousCauses (A) Amblyopia ex anopsia.lt has been amply dem onstrated that theuse of the centroscope is highly effective in restoring vision in an eyewhere the cause of the loss is due to disuse or non-function of the eye.Children with this kind of amblyopia will commonly demonstrate animprovement of one line (Snellen chart) of vision after a Week of hometherapy on the centroscope and continue to do this until normalvisionhas been achieved. Older children and, adults have shown the sameimprovement, though it may not be accomplished as quickly. ll/ianyformer patients with poor vision who were treated with conventionaltherapy and had. made little or no improvement, madegdramatic progresswith centroscope therapy.

(B) Amblyopia with aphakia.--The children and adults who had cataractssurgically removed andWho had reduced visual acuity with theircorrective lenses, improved their visionwith-centroscope therapy. With"the adults, the visual, improvement was notthe objective of thetherapy, but to restore central fixation to overcome an annoyingandinsuperable diplopia. The centroscope therapy did in fact overcomethe diplopia restoring the central fixation with the added benefit ofimproving the vision. V

tientswithhealed retinal pathology effecting the, central visionimproved the visual acuity with-centroscope therapy. One patient witha'healed central retinitis, asked to be put on centroscope therapy asanexperiment, after having been toldit was not indicated and thatimprove-Shedid intact improve her vision from 20/ 70- to 20/25 for near anddistance, after twomonths of work with the centroscope. The Waviness ofvision she experienced with this eye also disappeared and the imagesappeared normal in outline.

(D) Physiology ofiamblyopia ex anopsia.-I mage inhibition of one eyeoccurs in patients'with'strabismusyin an eye that deviates-in, out, upor down to avoiddiplopia,

thatis, seeing double (FIGURE 8). This-sensory phenomenon occurs in thehigher visual centers and is a compensatory-mechanism whereby the brainrefuses to recognize the messagefrom one eye, when this eye deviatesfrom its normal straight position or fusion position. Image inhibitionand rejection in thedeviating hibited when the. centroscope is heldvertically and the eye exposed while fixating centrally on the centerdot (FIGS. 1 and 7). The foveal area F must ofnecessity accept the imagesince the inhibited area between F and P cannot function. Thus, normalacceptance of. stimuli ,to the foveal area is established, and a normalresponse pattern can then be conditioned with repeated centroscopestimulus.

(2) Anomalous Retinal Correspondence This condition is variously calledanomalous sensorial relationship, abnormal retinal correspondence,anomalous spatial interpretation.

Thereare two aspects to vision; the motor and sensory.

The motor part is the looking,thernuscles moving the eyes for properimage reception on the foveas. The sensory is the seeing, or theinterpretation of what we see and where it is located in space. Thesensory seeing part of vision is in a developmental and learning stagepresumably, until the age of 7 years, when it has reached maturity, andfully conditioned.

-When an eye crosses orgets out of alignment with the other eye, it iscalled a motor anomaly. Thus, the sensory alignment does not fit intothis new eye position and consequently makes an adaptation to get rid orthe double vision. Thus, the first adaptation is the inhibition of theimage formed on the stimulated peripheral retinal receptor and also therejection of the different image formed on the. foveal area of this eye.After a period of time, a permanent re-alignment of the sensorymaladjustment has been so conditioned with usage, thus introducing asecond adaptation, the change in' thespatial or direction values in thedeviated eye to correspond to the deviated position of the eye ratherthan the straight position. This anomalousinterpretation does, notoccur-when only one eye is being used. and the other eye is covered, butoc curs only when the two eyes are seeingas a single unit. The. fixatingeyewill interpret .normally'the location of theooject in. space oftheimage formed on the stimulated retinal receptor, which would be thefovea. However, the image of thesame object is not formed on the foveaof the deviated eye, but on a peripheral, retinal receptor, which vhas adiiierentspatial or direction value from that of the fovea, namely thestraight head direction. With the anomalous adaptation, thestimulatedperipheral retinal area may now have the same spatial value asthe fovea of the fixating eye, that is, the straight ahead direction. Itis this peripheral retinalarea that is inhibited with the centroscope,thereby forcing fixation with the central area which is not inhibited.The. after-images also become .a frame of reference to, maintain centralfixation.

(3) Development or Restoration of; Fusion When images fall oncorresponding retinal areas they are fused into a singlementalimpression and projected mentally to the same place in space. It hasbeen assumedthat there is a center in the brain where fusion of thetwo-images occurs, in the same way one speaks of a center .for speech.We doknow, however, that fusion halves of a single organ, the cyclopeaneye (FIGURE 19).

The fovea of, this cyclopean eyegives us our egocentric localizationwith respect to the visual world around. us.

Frequently, in subjects with strabismus, it is found there is no fusion.Only one eye is used, the other eye sends no visual message to the brainand if it does, it is destroyed or rejected and not registered as avisual message." Many of these subjects never had fusion or binocularvision at birth, so we assume. Orthoptics, or visual training does notalter this situation for them. However, the use of the centroscope hasdefinitely established fusion in subjects where the techniques wereproperly employed.

It is presumed the use of the centroscope aids to establish fusion byremoving the previous stumbling blocks, namely, amblyopia suppressionand anomalous retinal correspondence.

(4) To Reduce Completely Eliminate the Deviatcd Position of One Eye inSlrabismus Because of the effects of the centroscope on the precedingconditions, namely, amblyopia, suppression and anomalous retinalcorrespondence, a strabismic eye (crossed, divergent, or verticallydivergent) will frequently straighten completely and remain straight ifproper follow-up orthoptic care is given. A few will do so withoutfollow-up orthoptic care. Those cases which do not straighten completelywill have some reduction in the amount of the deviation. This may be ofsignificance to the surgeon who is contemplating surgery on a strabismicpatient; it gives him information as to the type and amount of surgeryto be done since this differentiates the amount of deviation that isfunctional correctable with the centroscope, and that which ismechanical or muscular, which of course needs surgical measures for itscorrection.

In addition to the above-described usages, the present invention may beemployed to eliminate light sensitivity and to make uncomfortable eyescomfortable, especially those with presbyopia and where a convergenceinsufficiency exists.

TECHNIQUES The centroscope can be held by hand in front of either eye,in any position; vertically, horizontally or obliquely, or it can befanned in front of the eye to form segments of a circle. It is held inone position, 6 to 12 inches from the eye for a period of to 60 seconds,followed by a like procedure with the light held in another position infront of the same eye. For example, let us assume it is used in thetreatment of an amblyopic left eye. The light is held vertically at 8inches from the eye for seconds, the eye looking at the red dot 24. Thelight is then changed to the horizontal position and the eye views thecentral dot at 8 inches for seconds. The horizontal viewing is longerthan the vertical since it takes more stimulus to break down thesuppression in the retinal areas lying horizontal to the fovea. Thepatient then closes his eyes and soon the positive afterimages areperceived (FIGURE 9). Perhaps he will see only one or both horizontallines 21b, or only the vertical lines 21a, or he will see only onevertical and one horizontal line. Finally, he will see the two verticaland two horizontal lines with a space 23a in the center. The entireafterimage may be perceived only momentarily, then completely orpartially fade out. When he can see the cross with the space 23a in thecenter with his eyes closed, he then opens his eyes and fixates a smallletter M on a light colored wall about four feet distant. Gradually thenegative afterimages appear, or they may continue to be positive as hemay not be able to perceive a negative afterimage. In the case ofanomalous retinal correspondence, he can not locate the letter M in themiddle space 23a, but somewhere along the lateral or verticalafterimage, or even obliquely, at a 2, 4, 8 or 10 oclock position. Asthe negative afterimage becomes stronger and can be maintained forseveral minutes, from 4 to 20 feet distant from the fixated letter, thenboth eyes are stimulated.

In the treatment of image suppression let us assume the condition ofright esotropia with foveal and macular suppression or image inhibition,20/40 vision right eye, 20/40 left eye. The left eye remains coveredduring the entire procedure. Stimulate the right eye only with thecentroscope as follows:

Centroscope vertical, 60 seconds, light 6 inches from eye.

Centroscope horizontal, 60 seconds, light 6 inches from eye.

Do this 3 times daily, twice in succession each time, a total of 6exposures.

Following the exposure, the patient sees an afterirnage of cross withspace 23:: as long as possible afterwards, while viewing a letter on alight colored wall about 4 feet distant (FIGURE 9). A letter aboutone-half inch overall size is preferable since it approximates normalvisual acuity as measured at 20 feet. He then opens and closes his eyesalternately for IO-second periods. The afterirnage should be positivewith the eyes closed, negative with the eyes open. With the eyes closed,the cross will be seen white or yellow, with a space in the center, thespace representing the protected central foveal area. As the right eyefixates the letter M on the wall, the cross will be seen in a gradationof color until it appears as dark purple. The letter must be seen as clarly as possible, indicating foveal fixation. During the eyes openperiod, the patient backs off one stop, until he reaches a distance of20 feet from the letter, continuing to see the negative afterimages withthe letter in the central space and seeing the letter clearly. When theafterimages begin to fade, or he can no longer see the four imagessimultaneously, the entire procedure is repeated.

The above stated technique is the one employed at the present time toeliminate image inhibition and to establish central fixation. It variesaccording to the individual case, the amount of suppression, visual lossand eccentricity of fixation.

The treatment is confined to the retina of the deviating eye until: (1)the vision in the deviating eye has improved to 20/30 or better, and (2)the deviating eye can hold foveal fixation with the normal eyeuncovered. Then both eyes are stimulated: The normal left eye for 40seconds with the centroscope vertical; the deviating right eye for 60seconds with the centroscope horizontal. Following this stimulation thepatient, with eyes closed, sees the afterimage shown in FIGURE 9. Witheyes open and if no suppression is present, he sees two letters on thewall, the letter seen by the right eye having the horizontal afterimagesshown in FIGURE 12, the letter seen by the left eye having the verticalafterimages shown in FIGURE 11. As he straightens his eyes, the lettersmove closer together and when fixation with the two foveas has moved thedeviating eye to the center and the eyes are straight, the two images ofthe letter will fuse and the 4 afterimages form a cross around it asshown in FIGURE 10. During this procedure also, he opens and closes hiseyes alternately for 10-second periods. During the eyes open period, hecovers and uncovers the normal left eye 3 times to insure steady, fovealfixation with the right eye. When he fixates the right eye, the left eyemay deviate and if both eyes are seeing and not suppressing he sees twoimages of the letter on the wall.

Suppression is the precursor of amblyopia, and loss of fusion. All casesof strabismus must necessarily establish suppression to avoid diplopia.Suppression and/or amblyopia requires the same centroptic technique. Byeliminating suppression and establishing a normal stimulus-responsepattern, it is possible to: (1) Develop or restore fusion, (2)straighten the eyes in strabismus, (3) make uncomfortable eyescomfortable, and (4) eliminate light sensitivity or photophobia due tosuppression.

angle, double vision results.

When anomalous retinal correspondence exists there is a sensory as wellas motor change and therefore the sensory adaptation is interpreted asconforming with the changed eye posture. This means that the directionsign or spatial localization of the retinal elements in the deviated eyeis changed to function as if the eye were straight. Therefore, allstimulous with the centroscope is given to the deviating eye only untilthe anomalous sensory adaptation is eliminated and a normal spatiallocalization established. The deviating eye remains occluded at allother times. in this way the usage pattern of the deviated eye is brokenby dis-use. Exposure to the centroscope stimulates the'fovea to acorrect response and inhibits the peripheral retinal area in the sameeye from responding in the old erroneous manner, The after images assistin this maneuver by acting as a frame of reference and wiping theslate-clean as it were, on the area on which it is formed, so that theabnormal response pattern is inoperable. The inhibition caused by thebleaching of the visual purple in'the peripheral area makes possiblespatial induction. Inhibition in the peripheral area and'stimulates theeye to turn to the center for central and therefore foveal fixation.

In the treatment of anomalous retinal correspondence, let us assume acase of esotropia of 15, right eye, for centroscope therapy, and withvision 20/30 in right eye, and 20/20 in left eye. When, by means ofinstrumentation, the images are placed on the foveas at 15 A lesserangle or would bring the images together for the patient. The images,however, would not be imaged on corresponding retinal elements, i.e.,the two foveas. The patient would be fixating with the fovea of one eyeand a peripheral area of the other eye. The right eye remains occludedat all times except when receiving the centroscope stimulation. Duringcentroscope stimulation the left eye is oceluded and the right-eyestimulated, first with the centroscope in the vertical position for 60seconds, then'with the centroscope in the horizontal for 60 seconds.When he can elicit the afterimages, positively, in the form of a crosswith the central space 23a, then he endeavors to see the negativeafterimage with the central space 23a, as well as to see the smallletter M on the wall in that central space. When he can accomplish thisand the visual acuity has improved to 20/25 or better, and the fovealsuppression has begun to break down, then each eye is stimulatedseparately, not simultaneously, always keeping the non-stimulated eyecovered. When the letter M is correctly centered in the middle space 230of the cross, then both eyes are stimulated and remain uncovered whileviewing the negative afterimages. The centroscope stimulation is nowgiven as follows: Left eye first, light vertical, exposure time 50seconds. Right eye last, light horizontal, exposure time 60 seconds.Then the afterimages are perceived with the eyes closed. The image linesmay form a cross or they may be separated in a crossed position; theright horizontal images to the left of the vertical images seen by theleft eye. Also, the letter M is seen double, one with the vertical, onewith the horizontal afterimage lines. When the two images of the letterbecome fused in the middlespace and the 4 afterimage lines form a crossaround the central space, then the anomalous retinal correspondence ischanging to normal. The normal and anomalous may remain simultaneouslyfor a time. During this adjustment period the deviated eye may seedouble; a clear image is on the foveal and a dimmer image on theperipheral retinal area formerly associated with the foveal area of thenormal eye. As therapy proceeds, the dim mer peripheral image graduallyyields and disappears, leaving the foveal image to remain associated andfused with the foveal image in the other eye. This is Normal RetinalCorrespondence and a first goal of progress in therapy for anomalousretinal correspondence.

In the drawings andspecification, preferred embodii4 ments of theinvention have been disclosed and although specific terms are employed,they are used in a generic sense and not-intended for the purpose oflimitation, the scope of the invention being set forth in the followingclaims.

I claim:

1. Viewing apparatus for therapeutically treating the human eyecomprising: an opaque housing having a target opening therein forsubstantial optical alinement with the centralfoveal'macular area of theeye retina, a light source of high intensity mounted'in said housing, adark adaptive filter covering said opening and adapted to transmit abeam of red light rays containing approximately from 10 to 15 percent ofthe red portion of the visible spectrum from said source to said centralfovealmacular area and to filter the other light rays of the visiblespectrum from said beam, a second opening in said housing spacedadjacently from said first opening, said second opening so constructedand arranged to direct a beam of unfiltered light from said source ontoa peripheral retinal area of the eye, and means insaid space between theopenings for shielding an area of the eye retina adja cent the centralfoveal-macular area thereof from said high intensity light source.

2. Viewing apparatus for therapeutically treating the human eyecomprising: an opaque housing, a light source of high intensity mountedin said housing, means optically alinable with the centralfoveal-macular area of the eye retina for transmitting a beam of redlightrays containing approximately from 10 to 15 percent of the redportion of the visible spectrum fromsaid source onto said area, meansfor filtering the other light rays of the visible spectrum from saidbeam, means for directing a beam of unfiltered light from said sourceonto a peripheral retinal area of the eye, and means for shielding anarea of the retina intermediate said peripheral and centralfoveal-macular areas from said high intensity light source.

3. That method of therapeutically treating the human eye which comprisesthe concurrent steps of: exposing the central foveal-macular area of theeye retina to red light rays containing approximately from 10 to 15percent of the red portion of the visible spectrum to provide a fixationstimulus for the area, exposing to light of fixed intensity selectedperipheral retinal areas-angularly positioned respectively on linesextending radially from the foveal-rnacular area, the intensity of saidlight being sufficient for maximum inhibition of fixation and spatialorientation in said selected areas, and shielding from said inhibitinglight an area surrounding the exposed fovealmacular area and lyingradially inwardly from the exposed selected retinal areas.

4. That method of therapeutically treating the human eye which comprisesthe concurrent steps of: exposing the central foveal-macular area of theeye retina to a beam transmitting approximately from 10 to 15 percentlight to provide a fixation stimulus for the area, exposing to light offixed intensity selected peripheral retinal areas angularly positionedrespectively on lines extending radially from the foveal-macular area,the intensity of said light being sufiicient for maximum inhibition offixation and spatial orientation in said selected areas, and shieldingfrom said inhibiting light an area surrounding the exposedfoveal-macular area and lying radially inwardly from the exposedselected retinal areas.

5. That method of therapeutically treating the human eye which comprisesthe steps of: exposing to light of high intensity selected peripheralretinal areas of the eye located in predetermined positions relative tothe fovealmacular area there of to thereby bleach the visual purple ofthe selected areas to a visual white and to inhibit them fromre-stimulation, providing a fixation light stimulus to while sparing thefoveal-macular area from said inhibition and bleaching to cause thelatter area to become dark adapted, and subsequently exposing saidinhibited peripheral retinal areas and said dark adapted foveal-macular15 areas to a secondary light stimulus to thereby elicit in spacenegative afterirnagcs corresponding to the inhibited areas and at saidpredetermined positions.

6. That method of therapeutically treating the human eye which comprisesthe concurrent steps of: light adapting selected reference areas of theretinal lying radially of and defining the location of thefoveal-rnacular area of the eye, dark adapting the foveal-macular areaWhile supplying the latter with a fixation stimulus of filtered light,and shielding from light adaptation an area surrounding thefoveal-macular area and lying between the latter area and the selectedreference areas, and subsequently eliciting afterimages in space fromsaid reference areas defining the location of the foveal-macular area ofthe eye.

7. The method as set forth in claim 6 wherein said first step compriseslight adapting at least one area of the retina positioned horizontallyand radially of the foveal-macular area of the eye, and light adaptingat least one second area of the retina positioned vertically andradically of the foveal-rnacular area.

8. That method of therapeutically treating the human eye which comprisesthe concurrent steps of: stimulating the fovcal-macular area of the eye,and dark, adapting it, light adapting peripheral retinal areas definingthe location of the foveal-macular area with light of sufiicientintensity for maximum inhibition of fixation and spatial orientation ofsaid peripheral area, and shielding from said inhibiting light an areasurrounding the foveal-macular area and lying between the latter areaand said Peripheral retinal areas, and subsequently elicitingafterimages from said light adapted retinal areas defining in space thelocation of the foveal-rnacular area.

9. Viewing apparatus for therapeutically treating the human eyecomprising: a housing having an exterior opaque wall surface, a highintensity light source mounted within said housing, the opaque surfacedwall portion of said housing having an opening therethrough with theexterior end of the latter surrounded by said opaque surface, and meansfor transmitting through said opening a beam containing from 10 topercent light from said source, said housing having a plurality ofsecond openings therein spaced radially from said first opening andoperable concurrently with said first-named means to transmitrespectively a plurality of unfiltered light beams from said source, andsaid opaque surface surrounding said first opening being alined withsaid source to substantially interrupt light transmission along atubular path separating the first beam from the second beams, said firstand second light beams occupying fixed relative positions simultaneouslyalinable respectively with the fovealmacular area of the eye on onehand, and with selected peripheral retinal areas of the eye spaced fromand lyingradially of the foveal-macular area on the other hand.

10. Viewing apparatus as defined in claim 9 wherein said second openingscomprise a pair of elongated slots longitudinally alined with said firstopening, and wherein said light source comprises an elongated filamentextending substantially parallel to said alined slots and openmg.

11. That method of therapeutically treating the human eye whichcomprises the steps of: imparting a fixation light stimulus to thecentral foveal-macular area of the eye while sparing it from inhibitionand bleaching, concurrently exposing to light selected peripheralretinal reference areas defining the location of said foveal-maculararea, the intensity of said light being sufiieient to impart maximuminhibition of fixation and spatial orientation in the selected areas,and then exposing said inhibited reference areas to a secondary lightstimulus to elicit in space afterimages of similar configurations.

12. That method of therapeutically treating the human eye whichcomprises the concurrent steps of: light adapting at least a portion ofthe peripheral retinal area defining the location of the foveal-maculararea of the eye, dark adapting the foveal-macular retinal area of theeye, and subjecting the central portion of the fovealmacular area to afixating light stimulus whereby the dark adapted area will be inductedto remain in a fixed position during said light adapting and darkadapting steps, and the subsequent step of exposing said retinal portionto a secondary light stimulus to elicit afterirnages in spacecorresponding to the light adapted portion defining the location of thefoveal-macular area of the eye.

References Cited by the Examiner UNITED STATES PATENTS 2,098,990 11/37Newton 128-496 2,239,164 4/41 Wigelsworth 128-2X 2,803,246 8/57 Lange"128-765 2,930,379 3/60 Dopp 128-396 2,999,422 9/61 Papritz 3,036,5685/62 Stark 128-2 OTHER REFERENCES Glasser: Medical Physics, 1944, pages265-274, 1658- 1666. Medical Physics, 1960, Vol. 3 pages 601-603.

A. J. of Ophthalmology, October 1961, pages 474-479.

LOUIS R. PRINCE, Primary Examiner.

RICHARD J HOFFMAN, Examiner.

1. VIEWING APPARATUS FOR THERAPEUTICALLY TREATING THE HUMAN EYECOMPRISING: AN OPAQUE HOUSING HAVING A TARGET OPENING THEREIN FORSUBSTANTIAL OPTICAL ALINEMENT WITH THE CENTRAL FOVEAL-MACULAR AREA OFTHE EYE RETINA, A LIGHT SOURCE OF HIGH INTENSITY MOUNTED IN SAIDHOUSING, A DARK ADAPTIVE FILTER COVERING SAID OPENING AND ADAPTED TOTRANSMIT A BEAM OF RED LIGHT RAYS CONTAINING APPROXIMATELY FROM 10 TO 15PERCENT OF THE RED PORTION OF THE VISIBLE SPECTRUM FROM SAID SOURCE TOSAID CENTRAL FOVEALMASCULAR AREA AND TO FILTER THE OTHER LIGHT RAYS OFTHE VISIBLE SPECTRUM FROM SAID BEAM, A SECOND OPENING IN SAID HOUSINGSPACED ADJACENTLY FROM SAID FIRST OPENING, SAID SECOND OPENING SOCONSTRUCTED AND ARRANGED TO DIRECT A BEAM OF UNFILTERED LIGHT FROM SAIDSOURCE ONTO A PERIPHERAL